U.S. patent number 7,023,321 [Application Number 10/237,477] was granted by the patent office on 2006-04-04 for transmitting and receiving method, especially for detecting an id transmitter.
This patent grant is currently assigned to Siemens Aktiengesellschaft. Invention is credited to Alain Marc Bernard Brillon, Klaus Hofbeck, Johannes Ilg, Wolfgang Piesch.
United States Patent |
7,023,321 |
Brillon , et al. |
April 4, 2006 |
**Please see images for:
( Certificate of Correction ) ** |
Transmitting and receiving method, especially for detecting an ID
transmitter
Abstract
In a transmitting and receiving method, a request signal is
transmitted between a first and an additional transmitting and
receiving device by means of a bi-directional first communications
path. According to the request signal, a second communications path
is established for a predetermined time interval and the receiving
power in the additional transmitting and receiving device is
measured by means of a measuring device.
Inventors: |
Brillon; Alain Marc Bernard
(Villeneuve Tolosane, FR), Hofbeck; Klaus (Neumarkt,
DE), Ilg; Johannes (Regensburg, DE),
Piesch; Wolfgang (Regenstauf, DE) |
Assignee: |
Siemens Aktiengesellschaft
(Munich, DE)
|
Family
ID: |
7634107 |
Appl.
No.: |
10/237,477 |
Filed: |
September 9, 2002 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20030016140 A1 |
Jan 23, 2003 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
PCT/DE01/00870 |
Mar 7, 2001 |
|
|
|
|
Foreign Application Priority Data
|
|
|
|
|
Sep 3, 2000 [DE] |
|
|
100 11 509 |
|
Current U.S.
Class: |
340/5.61;
180/287; 307/10.2; 340/5.72 |
Current CPC
Class: |
G07C
9/00309 (20130101); G07C 2009/0038 (20130101); G07C
2209/63 (20130101) |
Current International
Class: |
G08C
19/00 (20060101) |
Field of
Search: |
;340/5.72,5.61,539,825.69,825.72 ;70/278 ;307/10.2,10.1
;180/278,287 ;455/67.11,424,561,115,226.2,562 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2537421 |
|
Jul 1976 |
|
DE |
|
3838657 |
|
May 1990 |
|
DE |
|
9410369 |
|
Nov 1994 |
|
DE |
|
43 29 697 |
|
Mar 1995 |
|
DE |
|
29607877 |
|
Sep 1996 |
|
DE |
|
4409167 |
|
Mar 1998 |
|
DE |
|
197 52 029 |
|
Jun 1999 |
|
DE |
|
19825702 |
|
Dec 1999 |
|
DE |
|
19927319 |
|
Dec 2000 |
|
DE |
|
19957536 |
|
Jun 2001 |
|
DE |
|
10038297 |
|
Mar 2002 |
|
DE |
|
0 848 123 |
|
Jun 1998 |
|
EP |
|
2749607 |
|
Dec 1997 |
|
FR |
|
2179751 |
|
Mar 1987 |
|
GB |
|
7057792 |
|
Mar 1995 |
|
JP |
|
9312190 |
|
Dec 1997 |
|
JP |
|
WO 99 59284 |
|
Nov 1999 |
|
WO |
|
Primary Examiner: Horabik; Michael
Assistant Examiner: Shimizu; Matsuichiro
Attorney, Agent or Firm: Baker Botts L.L.P.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation of copending International
Application No. PCT/DE/01/00870 filed Mar. 7, 2001, which
designates the United States, and claims priority to German
application number 10011509.8 filed Mar. 9, 2000.
Claims
The invention claimed is:
1. A method for transmitting and receiving signals between at least
one first transmitting and receiving device and at least one
further transmitting and receiving device, in particular for
unlocking and/or locking a vehicle, a) monitoring with the first
transmitting and receiving device, via a first communication path
of a given frequency, for the presence of the second transmitting
and receiving device, b) transmitting a request signal from the
first transmitting and receiving device via the first communication
path on detection of the second transmitting and receiving device,
c) setting up a second communication path of a lower frequency than
the frequency of the first communication path for a predetermined
time interval between the first and the second transmitting and
receiving devices as a function of the request signal, and d)
measuring the reception power level in the second transmitting and
receiving device by means of a measurement device.
2. A method as claimed in claim 1, wherein the measurement result
is transmitted via the first communication path to the first
transmitting and receiving device.
3. A method as claimed in claim 1, wherein the first transmitting
and receiving device or the second transmitting and receiving
device evaluates the measurement result by means of an evaluation
unit.
4. A method as claimed in claim 1, wherein the first and second
communication paths use high and low frequency bands,
respectively.
5. A method as claimed in claim 1, wherein a measurement amplifier
unit is connected in the second transmitting and receiving device
for setting up the second communication path.
6. A method as claimed in claim 1, wherein the start and duration
of the predetermined time interval are derived from information
content of the request signal.
7. A method as claimed in claim 1, wherein the second communication
path uses LF band.
8. A method as claimed in claim 1, wherein the second communication
path is unidirectional.
9. A method as claimed in claim 1, wherein, in order to identify
the position of the second transmitting and receiving device, steps
a) to d) are repeated a number of times using a different
transmission power.
10. A method as claimed in claim 9, wherein the measurement results
are evaluated in the first transmitting and receiving device by
means of an evaluation unit.
11. A method as claimed in claim 10, wherein the evaluation unit
evaluates the measurement results for detection of the second
transmitting and receiving device by means of a fixed table.
12. A method for transmitting and receiving signals between a first
transmitting and receiving device and a second transmitting and
receiving device for unlocking and/or locking a lock, said method
comprising: a) monitoring with the first transmitting and receiving
device, via a first communication path, for the presence of the
second transmitting and receiving device, b) transmitting a request
signal from the first transmitting and receiving device via the
first communication path upon detection of the second transmitting
and receiving device, c) setting up a second communication path for
a predetermined time interval between the first and the second
transmitting and receiving devices as a function of the request
signal, the start and duration of said predetermined time interval
derived from information content of said request signal, and d)
measuring the reception power level in the second transmitting and
receiving device.
Description
BACKGROUND OF THE INVENTION
The invention relates to a method for transmitting and receiving
signals between at least one first transmitting and receiving
device and at least one further transmitting and receiving device,
in particular for unlocking and/or locking a vehicle, as well as to
transmitting and receiving devices and an arrangement comprising
such devices for this purpose.
Methods such as these as well as transmitting and receiving devices
are used, for example, in vehicle technology in order to allow the
vehicle or the vehicle doors to be unlocked and/or the antitheft
device to be deactivated in a manner which is as convenient as
possible for an operator.
Passive access systems are being increasingly used for this
purpose, in which an operator carries an ID transmitter with him
which, in contrast to active systems, need not be operated by means
of a button or the like, but communicates automatically with a
corresponding base station which is located in the vehicle, as soon
as the distance between the ID transmitter and the vehicle or the
base station falls below a specific value.
Active and, in particular, passive, electronic key-operated systems
such as these, which are generally based on the use of radio, are
subject to stringent security requirements with regard to
unauthorized access, with a power consumption which is as low as
possible generally being desirable, since the power sources for the
ID transmitter and/or base station are generally autonomous, in
order to ensure operation even over a lengthy time period.
SUMMARY OF THE INVENTION
The present invention is therefore based on the object of providing
a method for transmitting and receiving signals between at least
one first transmitting and receiving device and at least one
further transmitting and receiving device, as well as a
transmitting and receiving device and an arrangement for this
purpose, which ensure a high level of security with regard to
unauthorized access, while at the same time having a power
consumption which is as low as possible.
According to the invention, this object is achieved by a method for
transmitting and receiving signals between at least one first
transmitting and receiving device and at least one further
transmitting and receiving device, in particular for unlocking
and/or locking a vehicle, a) with the presence of the further
transmitting and receiving device being monitored by the first
transmitting and receiving device by means of a bidirectional first
communication path, b) the first transmitting and receiving device
transmitting a request signal via the first communication path on
detection of the further transmitting and receiving device of this
further transmitting and receiving device, c) a second
communication path being set up for a predetermined time interval
between the first and the further transmitting and receiving device
as a function of this request signal, and d) the reception power
level in the further transmitting and receiving devices being
measured by means of a measurement device.
According to an embodiment of the present invention a transmitting
and receiving device has a first transmitting and a first receiving
unit for a first communication path with at least one further
transmitting and receiving device, wherein the transmitting and
receiving device has at least one further transmitting and/or
receiving unit which can be switched on and off and has a
measurement device in order to measure the reception power of a
further transmitting and receiving device.
An arrangement according to the present invention comprises at
least a first transmitting and a first receiving unit for a first
communication path and at least one further transmitting and
receiving device which can be switched off.
The setting up of at least one further communication path for only
a predetermined time interval as a function of a request signal
which is transmitted via a first communication path makes
undesirable recording or monitoring of the communication more
difficult, since communication such as this is not expected based
on the prior art.
The method according to the invention now makes it possible to set
up a second communication path which, although its power
consumption is higher, nevertheless offers a high level of
protection for this purpose against unauthorized access by means of
direct or indirect imitation of an access code. The high power
consumption advantageously occurs only during a predetermined,
short time window, which is in the microsecond range, so that the
overall power consumption resulting from this very short-term
greater power consumption, which occurs only when a valid request
signal is received, increases only insignificantly.
The second communication path may accordingly be set up both
bidirectionally and unidirectionally, in which case, since the time
interval is short, it is also possible to use very high
power-consumption transmission methods, such as very high
frequencies, high amplitudes at the transmitter end or very
sensitive, high-power receivers which are designed, for example,
using measurement amplifier units.
It is particularly advantageous for the second communication path
to be set up as an LF system, in which the signals are transmitted
essentially by means of magnetically inductive coupling. Since a
base station which is located in a vehicle is normally intended to
cover a certain area, for example with a diameter of 1 to 3 meters,
in which an ID transmitter can be detected, systems such as these
have a very high power consumption.
In order to set up a functioning communication path at least
unidirectionally, appropriate antennas, for example frame antennas,
can be used at the transmitter end in the base station, and may be
operated at high power levels, via power amplifiers.
At the receiving end in the ID transmitter, the receiver can be
made more sensitive by means of a measurement amplifier unit, thus
resulting in an increase in range in conjunction with normal LF
transmitters (without power amplification) and, in particular,
making it possible to achieve a greater range by means of the
amplified-power LF transmitters mentioned above.
In contrast to systems (which are generally in higher frequency
bands) with a strong electrical field component, magnetically
inductive coupling is advantageously not influenced or interfered
with by organic material and reflections. The predetermined time
interval in a very short time window furthermore means that
interference outside this time window is ignored, so that these
measures considerably improve the interference immunity of the
overall system. Owing to the lack of shielding and reflection of
the predominant magnetic field component, it is also possible to
set an accurate range irrespective of local characteristics and
objects or people in this area, so that it is advantageously
possible to avoid anomalous propagation and correspondingly
undesirable initiation effects.
If the LF communication path is made possible with an appropriate
range by using a measurement amplifier unit at the receiver end,
then it is also possible to transmit at a lower power level at the
transmitter end and to reduce the power consumption at the
transmitter end, so that the power source in the vehicle, for
example the battery, is loaded to a lesser extent. A reduced
transmitter power also results in a reduced radiation load and
hence in reduced radiated interference affecting other components,
while at the same time avoiding any health risks.
According to the method on which the invention is based, the
reception power in the further transmitting and receiving device,
that is to say for example an ID transmitter, is measured by means
of a measurement device. Various embodiments are feasible for this
purpose, for example in the form of one or more threshold values
which, when reached, result in actions such as indication of this
threshold value, storage of the threshold value, evaluation of a
number of received threshold values or else the transmission of
such measurement results or in evaluations to the at least one
first transmitting and receiving device, for example the base
station in a vehicle.
The corresponding evaluations and actions as a function of this,
such as the locking or unlocking of the doors, the activation or
deactivation of the antitheft device, can in consequence also be
carried out by the base station, by means of appropriate control
units.
The start of the predetermined time interval need not, of course,
coincide with the time at which a request signal is correctly
received, but may also be offset in time by a predetermined time
interval. In this case, it is also feasible to integrate a future
time for the start of the time interval as information in the
request signal. The duration of the predetermined time interval may
be predetermined or adjustable via appropriate electronic devices,
for example an RF element or an appropriate digital counter in the
ID transmitter, or may likewise be included as information in the
request signal.
The method according to the invention is particularly advantageous
if it carried out more than once using different parameters, and
corresponding measurement results are determined. By way of
example, the transmission power and/or the receiver sensitivity may
be changed, and/or may be varied by physically different
transmission areas, for example by means of a number of antennas or
combination antennas, which are arranged at physically different
locations and have different emission angles.
The corresponding measurement results may then be transmitted
individually to the other transmitting and receiving device, or may
be collected in advance and transmitted in a block. In this case,
it is also feasible for more detailed evaluation of these
measurement results not only to be carried out in the at least
first transmitting and receiving device, but also to be carried out
in the further transmitting and receiving device, before
transmission, as a final or intermediate result.
In a further advantageous refinement of the invention, field
distortion and calibration values for the transmitting and
receiving device may be used in order to evaluate the received
field strength values as exactly as possible, by means of a table
which is stored, for example, as a data item in an evaluation
unit.
In contrast to the second, high power consumption, communication
path, which is set up via a transmitting and/or receiving unit,
which can be switched on, between at least two transmitting and
receiving devices, the first communication path is advantageously
set up as a very low-power communication path. In the case of
conventional RF systems, this is the case in the MHz band, for
example at 433 MHz or 867 MHz, which can advantageously be
implemented in a highly space-saving manner and highly
cost-effectively since this is in widespread use.
Further advantageous refinements of the invention may be found in
the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be explained in more detail in the following
text with reference to an exemplary embodiment which is illustrated
in the drawing. In the drawing:
FIG. 1 shows a schematic block diagram of a base station located in
a motor vehicle, and
FIG. 2 shows a schematic block diagram of an ID transmitter.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The base station which is illustrated in FIG. 1 has a control unit
1, a transmitting unit 3, a receiving unit 5 and an LF transmitter,
for example a ping generator 7. The transmitting unit 3 is in this
case connected to a schematically illustrated antenna 4, in the
same way that the receiver unit 5 is connected to its antenna 6. It
is, of course, feasible for the transmitting unit 3 and receiving
unit 5, which are illustrated separately here, to be in the form of
a combined transmitting and receiving unit, which is either
connected to a transmitting antenna 4 and to a receiving antenna 6,
or has a single antenna which acts both as a transmitting antenna
and as a receiving antenna. As a further transmitting unit, the
base station has a so-called ping generator 7 which transmits a
very low-frequency field, in the LF band, for example at 100 to 300
KHz and with a predominantly magnetic field component, via its
antenna 8, for example in the form of a frame antenna.
In the same way as the base station, the ID transmitter which is
illustrated in FIG. 2 has a control unit 10, a receiver unit 13 and
a transmitting unit 15, which are each connected to their antennas
(receiving antenna 14 and transmitting antenna 16). In contrast to
the base station, the ID transmitter has, instead of an LF
transmitter, an LF receiver 17, in the form of a ping receiver,
which can produce magnetically inductive coupling via its receiving
antenna 18 in conjunction with the ping generator 7 and the
transmitting antenna 8 of the base station.
As described above for the base station, it is also possible,
rather than using a separate transmitting unit 15 and receiving
unit 18, to use a combined transmitting and receiving unit with one
transmitting and receiving antenna or separate transmitting and
receiving antennas 14 and 16.
When an ID transmitter is located in the area of the base station,
then bidirectional communication (first communication path) takes
place via the transmitter 3, 15 and receiver units 5, 13, for
example in the low power consumption RF band, in which case, as in
conventional systems, an ID transmitter can be detected when it is
within a certain vicinity.
In contrast to this result, which is relatively uncertain as a
result of anomalous propagation, reflections, shielding or even
unauthorized access actions, the method according to the invention
means that the detection and, as a function of this, an appropriate
action such as locking/unlocking of the doors,
activation/deactivation of the antitheft device take place only
when a further result has been successfully transmitted and
appropriately evaluated.
For this purpose, on detection of an ID transmitter by means of the
first communication path, the base station uses this first
communication path to send a request signal, which signals to the
ID transmitter that a signal will be transmitted at a specific time
within a short time window via a second communication path.
An LF path is in this case chosen as the communication path, which
advantageously allows magnetically inductive coupling, which is
subject to only a lesser extent, if at all, to the above mentioned
disadvantages, such as shielding, reflection and unauthorized
intervention.
In the simplest embodiment as illustrated, the base station has
only one ping generator 7 and the ID transmitter has only one ping
receiver 17, so that this further communication path is only of a
unidirectional nature. At the signaled time, the base station
switches the ping generator 7 on via its control unit 1, and the
ping generator 7 emits the magnetically inductive signal via its
frame antenna 8.
Furthermore, in the ID transmitter, the ping receiver 17 is
switched on by means of the control unit 10 at the signaled time,
likewise for a short time interval, which is advantageously
essentially at the same time, and, by means of its antenna 18,
receives the signal transmitted from the ping generator 7 in the
base station.
In order to keep transmission power of the ping generator in the
base station as low as possible, so that other components are
advantageously subject to less radiated interference and so that
low-cost components can be used, the ID transmitter has a
measurement amplifier, which is not shown in any greater detail in
FIG. 2, for correct reception of such a signal at a reduced
transmission power.
This measurement amplifier, which may be integrated in the ping
receiver 17 or in the control unit 10 or may be arranged as an
autonomous unit in the path from the frame antenna 18 to the
control unit 10, appropriately increases the sensitivity of the
ping receiver 17, in order to allow this magnetically inductive
communication path to be set up correctly within a desired area,
for example within several meters, and in particular within one to
three meters.
The reception power level is in this case determined in the ID
transmitter by means of a measurement unit, which is not
illustrated in any greater detail, for example in the form of a
threshold value or threshold values which can be reached in
different ways. At the end of the time interval, the communication
path is interrupted both in the base station and in the ID
transmitter, by switching off the ping generator 7 and the ping
receiver 17, and/or the measurement amplifier which is not
illustrated.
The determined measurement result is then signaled by the ID
transmitter via the first communication path, that is to say the
transmitter 15, the receiver 5 of the base station, and is used by
this base station, if received correctly, to unlock the doors
and/or deactivate the antitheft devices.
Conversely, it is feasible to allow the opposite actions to be
carried out, that is to say the locking of the doors and activation
of the antitheft device, either when the doors are actually closed
or only when a failed attempt is made to use the second
communication path.
The capabilities of the system can be further enhanced if the steps
which have been mentioned comprising the "request signal", and
"transmission of a signal via at least one further communication
path" and "measurement of the reception power level" are carried
out more than once, since, for example, this allows the speed of
approach to be determined via one and the same antenna 8 on the
basis of different results.
It is also feasible to fit a number of frame antennas 8 in the
vehicle so that transmission fields are transmitted via one or more
ping generators 7, which are connected to these frame antennas 8,
from different locations in the vehicle, for example the left-hand
door, right-hand door, tailgate etc., and for the position of the
ID transmitter, that is to say the direction with respect to the
base station, to be detected as a function of the reception power
levels detected in the ID transmitter, which are either signaled
individually to the base station as the result or are collected in
advance in the ID transmitter where they may be subjected to
partial or full evaluation, or may be subjected to such evaluation
in the base station.
This not only avoids dead angles, but also allows different actions
to be carried out, such as unlocking of the left-hand door when
approaching from the left, unlocking of the right-hand door when
approaching from the right, unlocking of the tailgate or of the
trunk on approaching from the rear, etc., to be carried out as a
function of the direction and/or of the above-mentioned speed of
approach.
Although the described exemplary embodiment has been used to
explain the method according to the invention on the basis of a
passive access system for a motor vehicle, it can, of course, also
be used for an active access system, that is to say for setting up
the first communication path on the basis of operation of a button
or the like in the ID transmitter. Furthermore, the method
according to the invention as well as an arrangement of the
transmitting and receiving devices according to the invention for
carrying out such a method are not restricted to vehicle
technology, but may be used in many fields, such as building
technology, monitoring technology, counting systems etc.
By way of example, access controls such as these may also be used
for house doors, garage doors etc. On the other hand, instead of
being used for access control, the invention can also be used for
secure detection of a transmitting and receiving device for
monitoring moving objects, such as people, where such a moving
object is located, or how often it passes specific positions
(counting systems).
* * * * *